Dynamic expansion of container space size for Docker advanced applications

The default space for the Docker container is 10G, and if you want to specify the size of the default container (specified when you start the container), You can specify it in the Docker configuration file via the Dm.basesize parameter, such as

docker-d--storage-opt dm.basesize=20g

is to specify a default size of 20G, the specific parameters can refer to Https://github.com/docker/docker/tree/master/daemon/graphdriver/devmapper

The above method is just the time to actually build the container, and after the modification needs to restart Docker, unable to dynamically specify the size of the running container, let me explain how to dynamically expand the size of the container space.

Benefits of Dynamic Scaling:

1, do not need to modify the Docker configuration, and restart the Docker service;

2, can be directly to the operation of the container dynamic expansion (can only increase, can not be shrunk);

Disadvantages:

1. The format of Docker host partition must be ext2, ext3, Ext4;

2. The Docker storage engine must be devicemapper

Storage Engine view, you can use Docker info to view

15:25:49 # docker Infocontainers:5images:62storage driver:devicemapper Pool name:docker-8:17-37748738-pool Data file: /data1/docker/devicemapper/devicemapper/data Metadata file:/data1/docker/devicemapper/devicemapper/metadata data  Space used:21498.9 MB Data Space total:102400.0 MB Metadata Space used:13.7 MB Metadata Space total:2048.0 mbexecution Driver:lxc-1.0.6kernel version:3.10.0-123.el7.x86_64

From the storage driver above you can see the engine I'm using.

The following is an example of a dynamic extension:

1. Create a new test Container

15:23:48 # docker run --privileged -d  -p 22 --name= ' Test '   docker.ops-chukong.com:5000/centos6-http:new /usr/bin/ Supervisord1716fe941926dbd0b247b85d73e83b9465322a5005edc3c6182b59a6ac0939a7[email protected]:/tmp15:24:01  # docker inspect test|grep -i add          "IPAddress":  "172.17.0.18", [email protected]:/tmp15:24:08 # ssh 172.17.0.18the  authenticity of host  ' 172.17.0.18  (172.17.0.18) '  can ' t be established . rsa key fingerprint is 39:7c:13:9f:d4:b0:d7:63:fc:ff:ae:e3:46:a4:bf:6b. are you sure you want to continue connecting  (yes/no)?  yesWarning : permanently added  ' 172.17.0.18 '   (RSA)  to the list of known  hosts. [email protected] ' s password:last login: mon nov  17 14:10:39 2014 from 172.17.42.1[email protected]:~15:24:13 # df - Htfilesystem           type    size   Used Avail Use% Mounted onrootfs                rootfs  9.8G  470M  8.8G    5% //dev/mapper/docker-8 :17-37748738-1716fe941926dbd0b247b85d73e83b9465322a5005edc3c6182b59a6ac0939a7                      ext4     9.8G  470M  8.8G   5% /shm                   tmpfs     64m     0   64m   0% /dev/shm/dev/sdb1            ext4    1.8t    30G  1.7T   2% /.dockerinit/dev/sda3             ext4    518G   30G   462G   6% /etc/resolv.conf/dev/sdb1             ext4    1.8T   30G  1.7T    2% /etc/hostname/dev/sdb1             ext4    1.8t   30g  1.7t   2% /etc/hosts/dev/ sdb1            ext4    1.8t    30g  1.7t   2% /.dockerenv

You can see that the root partition where I run the Test container is the EXT4 partition, the container is 10G

2. Use my script to dynamically expand container space

Script Content

15:22:12 # cat dynamic_modify_docker_disk.sh#!/bin/bash#this script is dynamic  MODIFY DOCKER CONTAINER DISK#AUTHOR DENG LEIIF [ -Z $1 ]  | |  [ -z $2 ]; then    echo  "usage: container_name  Increase_capacity "    echo " example: i want increase 11g to  test "    echo " the command is:   sh  ' basename  $0 '  test 11 '     exit 1                                                   fiif [  ' docker inspect $1 &>>/dev/null  &&  echo 0 | |  echo 1 '  -eq 1 ];then    echo  ' the container $1  is no exist! " Exit 1ficontainer_id= ' docker inspect -f  ' {{ . ID&NBSP}} '  $1 ' now_disk= ' dmsetup table /dev/mapper/docker-*-$container _id|awk  ' {print  $2} ' disk=$ (($2*1024*1024*1024/512)) if [  $disk  -lt  $now _disk ];then     echo  "I can ' t shink container $1 from $ ($now _disk*512/1024/ 1024/1024)) g to ${2}g! i only modify contanier increase disk! " exit 1fidmsetup table /dev/mapper/docker-*-$container _id|sed  "s/0 [0-9]* thin/0   $disk  thin/"|dmsetup load /dev/mapper/docker-*-$container _iddmsetup resume /dev /mapper/docker-*-$container _idresize2fs /dev/mapper/docker-*-$container _idif [ $? -eq  0 ];then    echo  "Dynamic container $1 disk to ${2}g is success!" else    echo  "Dynamic container $1 disk to ${2}g is  fail! " Fi

Currently adding 20G space dynamically to the Test container

15:24:40 # sh dynamic_modify_docker_disk.sh test 20dynamic container test  disk to 20g is success! [email protected]:/tmp15:24:46 # ssh 172.17.0.18[email protected] ' S password: last login: tue jan 20 15:24:13 2015 from 172.17.42.1[email  protected]:~15:24:52 # df -htfilesystem            type    size  used avail use% mounted onrootfs                rootfs    20g  475m   19g   3% //dev/mapper/docker-8 :17-37748738-1716fe941926dbd0b247b85d73e83b9465322a5005edc3c6182b59a6ac0939a7                      ext4     20g  475m   19g   3% /shm                   tmpfs     64m     0   64m   0% /dev/shm/ dev/sdb1            ext4     1.8t   30g  1.7t   2% /.dockerinit/dev/sda3             ext4    518g   30g   462G   6% /etc/resolv.conf/dev/sdb1             ext4    1.8T   30G  1.7T    2% /etc/hostname/dev/sdb1             ext4    1.8t   30g  1.7t   2% /etc/hosts/dev/sdb1             ext4    1.8T   30G   1.7t   2% /.dockerenv

You can see that you've added success

The following is added to the test to 50G

15:25:21 # sh dynamic_modify_docker_disk.sh test 50dynamic container test  disk to 50g is success! [email protected]:/tmp15:25:24 # ssh 172.17.0.18[email protected] ' S password: last login: tue jan 20 15:24:52 2015 from 172.17.42.1[email  protected]:~15:25:27 # df -htfilesystem            type    size  used avail use% mounted onrootfs                rootfs    50g  480m   47g   1% //dev/mapper/docker-8 :17-37748738-1716fe941926dbd0b247b85d73e83b9465322a5005edc3c6182b59a6ac0939a7                      ext4     50g  480m   47g   1% /shm                   tmpfs     64m     0   64m   0% /dev/shm/ dev/sdb1            ext4     1.8t   30g  1.7t   2% /.dockerinit/dev/sda3             ext4    518g   30g   462G   6% /etc/resolv.conf/dev/sdb1             ext4    1.8T   30G  1.7T    2% /etc/hostname/dev/sdb1             ext4    1.8t   30g  1.7t   2% /etc/hosts/dev/sdb1             ext4    1.8T   30G   1.7t   2% /.dockerenv

can also increase success

But if I shrink to 30G,

15:25:45 # sh dynamic_modify_docker_disk.sh test 30I can ' t shink container test from 50G to 30g! I only modify Contanier increase disk!

is not scaled down and can only be added to the operation.

As for the principle of dynamic increase, please refer to http://jpetazzo.github.io/2014/01/29/docker-device-mapper-resize/

FAQ:

When using Docker in CentOS 7, the default storage engine is Devicemapper

When you dynamically resize the Docker container disk space, it appears

RESIZE2FS 1.42.9 (28-dec-2013) Resize2fs:device or resource busy while trying to open/dev/mapper/docker-253:1-1270544-d2 D2cef71c86910467c1afdeb79c1a008552f3f9ef9507bb1e04d77f2ad5eac4couldn ' t find valid filesystem superblock.

The reason is that RESIZE2FS only supports ext2, ext3, Ext4, and does not support XFS

Therefore, it is recommended that the file system format of the Docker server be adjusted to EXT4

This article is from the "Yin-Technical Exchange" blog, please be sure to keep this source http://dl528888.blog.51cto.com/2382721/1606170

Dynamic expansion of container space size for Docker advanced applications